A gas turbine engine may be used to power aircraft or various other types of vehicles and systems. Such engines typically include a compressor that receives and compresses incoming gas such as air; a combustor in which the compressed gas is mixed with fuel and burned to produce high-pressure, high-velocity exhaust gas; and one or more turbines that extract energy from the exhaust gas exiting the combustor.
There is an increasing desire to reduce gaseous pollutant emissions, particularly oxides of nitrogen (NOx), that form during the combustion process. One approach to reduce NOx emissions is the implementation of a rich burn, quick quench, lean burn (RQL) combustion concept. A combustor configured for RQL combustion includes three serially arranged combustion zones: a rich burn zone at the forward end of the combustor, a quench zone downstream of the rich burn zone, and a lean burn zone downstream of the quench zone. By precisely controlling the stoichiometry between the air and fuel in each of these zones, NOx emissions can be minimized.
In addition to reducing emissions, combustor designers further attempt to manage the temperature characteristics of the combustion process, which is particularly difficult in an RQL combustor. High temperatures may cause thermal stresses and other problems. While increased cooling flows may improve cooling, such additional air flow may interfere with the stoichiometries of the RQL combustion process. One such component that may be susceptible to high temperature issues is the fuel injector shroud that surrounds a fuel injector within the combustion chamber. During operation the fuel injector shroud directs air to the nozzle of the fuel injector for mixing prior to combustion. Improvements with respect to the durability and air flow conditioning characteristics of such fuel injector shrouds are desirable.
Accordingly, it is desirable to provide gas turbine engines with improved fuel injector shrouds. In addition, it is desirable to provide fuel injector shrouds with improved air flow and durability characteristics. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.